Improvement in coating metals with platinum



UNITED STATES PATENT Onrrcn.

JEAN B. A. DODE, OF REIMS, FRANCE.

IMPROVEMENT .lN COATING METALS WITH PLATINUM.

Specification forming part of Letters Patent No. 219,807, datedSeptember 23, 1879; application filed November 30, 1878 patented inEngland, January 19, 1877.

To all whom it may concern:

Be it known that I, J EAN BAPTISTE ALEX- ANDRE Donn, of Reims, France,have invented Improvements in Coating Metals with Platinum;*and I dohereby declare that the following is a full, clear, and exactdescription of the same.

Many attempts have been made to give metals a coating capable ofpreserving them from oxidation when exposed to the air, to fire, or tothe action of gaseous acids; but the processes at present in use givebut imperfect results. Plating with copper, nickel, silver, or tin, byimmersion or by electro-deposition, is insufficient to preventoxidation, which goes on notwithstanding, although relatively highprices are charged for the articles so plated. The articles to which Imore particularly refer are those made of cast-iron.

After having examined and considered all methods heretofore proposed, Ihave directed my attention to the employment of platinum in asufficiently-divided. state to admit of its being used as a preventiveof oxidation, and that at a cost considerably lower than that of themethods now in use. To this end I have, after many experiments, devisedthe following process: First operatiow-I make a mixture of "tenkilograms of borate of lead and two kilograms of oxide of copper, in agrinding-mill, by adding enough spirits of turpentine to render theproduct sufficiently fluid to be applied to the articles to be coated.When I deem the mixture complete, I place it in a cast-iron kettle, andadd to it fifty grams of neats-foot or other suitable oil. The kettle isexposed to a gentle heat, in order to render the mixture very fluid andavoid the necessity of adding a large quantity of spirits of turpentine.

When the composition is lukewarm it may be used in the following manner:The article or piece of metal to be platinized, if of castiron, shouldfirst be cleaned of any sand from the mold which may remain in thecavities of the article 5 but if of wrought or rolled iron it is simplynecessary to remove the dust or other foreign matter adhering thereto.It is unnecessary to disturb any portions of the surface that maybealready oxidized, as this in no way interferes with the operation. Ahorsehair brush is then dipped into spirits of turpentine, and theentire surface of the article thoroughly brushed over therewith, carebeing taken to leave no parts untouched, and the article is then allowedto stand until the turpentine has partly dried, after which the mixture,prepared as above described, and which must be kept lukewarm, isapplied. For this purpose, a large and sufficiently hard brush is dippedinto the composition, and the latter is applied by brushing and dabbingthe surface of the article therewith. Care should be taken to lay on thecomposition as evenly as possible, and the coat should be very thin, asit is only intended to prepare the metal to which it is applied toreceive the platiniferous coating, hereinafter described, and toprevent, more especially in the case of castiron, the absorption of toolarge a quantity of platinum. A thin coat is also advisable in the caseof a molded form, so as to avoid filling up the cavities of the designand destroying its sharpness. This done, the article is placed in adryingoven or muffle, built of sheet-iron, cast-iron, or brick-work, andof a construction to suit the article to be platinized. This oven ormuffle is highly heated, in order to fix the composition, which by theaction of the fire becomes a fine dark-green and very lustrous. Thearticle is then allowed to cool, when it is ready to be platinized bythe following process:

Second 0pemt'i0n.-I mix intimately ten kilograms of borate of lead withfive kilograms of German litharge by grinding themas fine as possible ina mill, as in the previous case, having care to thoroughly moisten themixture with a certain quantity of oil of lavender or other essentialoil. I then collect the product in an enameled cast-iron pot, and let itstand for some hours. During this time I prepare in another enamelediron pot the following mixture, viz: Five kilograms of dry chloride ofplatinum, upon which I pour two kilograms .of common ether. The etherdissolves the chloride of platinum, and as soon as this is effected Ipour in slowly (having care to stir the mixture well with an enamelediron spatula while doing so) fifteen kilograms of oil of lavender. Whenthis mixture is complete I cover the kettle, and let it stand for thirtyminutes. I then take the kettle into the open air and re move the cover,so as to allow the ether to evaporate, the oil of lavender aloneremaining with the platinum held in suspension therein. I slowly pourthe platiniferous product ob tained on the mixture of borate of lead andlitharge, stirring briskly the while. When completely mixed I add twentykilograms of amylic alcohol, and when the whole is mixed together theplatiniferous composition is ready for use.

To platinize the article coated or prepared as described under the firsthead, it is dipped into the platinif'erous composition to cover it witha very thin coating. The composition is allowed to drain off, and whenit has become sticky, if there are any deep cavities, as in the case ofa molded form, a small brush or pencil should be used to remove thelarge drops, which would, if allowed to remain, mar the appearance ofthe article. The article is then placed in a similar oven or muflie tothat above mentioned care being taken not to raise the temperature to sohigh a degree. The article is then left to cool, and when removedpresents the appearance of fine silver-white.

By applying this platiniferous composition to articles of enameledcast-iron, either by dipping or by means of a brush, similar effects maybe obtained.

I claim- 1. The process herein described of platinizing metal, whetherenameled or not, by the employment of a mixture in which the platinum isheld in suspension in an essential oil, substantially as specified.

2. The process, as herein described, for coating metals with platinum,and which consists, first, in brushing over the article of metal withspirits of turpentine; secondly, in coating the article with a layercomposed of a mixture of borate of lead and oxide of copper, and dryingsame in an oven; and, thirdly, in dipping the article thus prepared in acomposition of borate of lead, German litharge, platinum-chloride,ether, oil of lavender, and amylic alcohol, and afterward submitting theobject so coated to the action of beat, all as specified.

JEAN BAPTISTE ALEXANDRE DODE.

Witnesses:

GEORGES KRAUs, EUGENE Harmer.

